APOE-containing rHDL and lipid-free rhAPOE, but not APOE-depleted HDL, decrease emTreg apoptosis. Purified bulk Treg subsets were incubated with total HDL or APOE-depleted HDL, APOE(2–4)-containing rHDL, or lipid-free rhAPOE(2–4), overnight in X-VIVO medium. A: 4–15% SDS-PAGE analysis of APOE-containing HDL (APOE HDL, lane 1) and APOE-depleted HDL (APOE-depleted HDL, lane 2). B: Caspase 3/7 expression of emTreg incubated with APOE-depleted HDL or total HDL. The data are normalized with respect to the level of caspase expression in the control (PBS). Asterisks indicate significant differences (∗∗P < 0.005) in t-test (n = 5). Caspase 3/7 expression of emTreg after treatment with (C) rHDL-APOE(2–4)-POPC and (D) rhAPOE(2–4). The data are normalized with respect to the level of caspase expression in the control (PBS). Asterisks indicate significant differences (∗P < 0.05, ∗∗∗P < 0.001) in one-way ANOVA test (n = 4–6). E: Caspase 3/7 expression of emTreg after the treatment with different concentrations of rHDL-APOE(3,4)-POPC, dotted line shows the mean of total HDL treatment (700 μg/ml of protein). Asterisks indicate significant differences (control vs. rHDL-E-POPC) in two-way ANOVA (∗P < 0.05, ∗∗P < 0.005, ∗∗∗P < 0.0005) (n = 5).